This invention relates to the field of water faucets for use in sinks and the like and more particularly to faucets that turn on or off automatically.
Water faucets that will turn off by themselves have been used for years in public lavatories in order to guard against the waste of water due to faucets being left on accidentally. Where both hot and cold water is available from the faucet, it is doubly important to prevent the waste of hot water since energy must be consumed to heat the water.
The shut-off mechanisms used in the past have usually been spring loaded return devices in the valve mechanism itself. The valve itself may take the form of a spring loaded knob which the user turns approximately one quarter to one half a turn. When the knob is released by the user it returns to its off position. Alternatively the knob may be one which the user pushes to cause water to flow. In either of these types of faucets a delay mechanism may be built in so that the water will flow for a predetermined amount of time after the knob is released so that the user may wash both hands together. This solution is seldom completely satisfactory because the amount of delay may be too little for some users and for others it may be more than necessary, thus wasting water.
There are many industrial applications for water faucets where it is desirable to have a valve mechanism which can be turned on and off without having to use the user's hands. For example, in hospitals, laboratories and industrial work areas of various types one often finds foot or knee operated faucets. These allow the user to wash his hands or objects in his hands without having to operate a faucet control with his hands. This is often necessary for sanitary as well as convenience reasons. However, these types of faucets can be allowed to run longer than is required, thus wasting water.
Home use also accounts for a significant amount of water usage. It is not uncommon for water to be left running while a person does another task and then returns to the sink. Handicapped persons also frequently have difficulty in using standard faucets in an economical manner, and sometimes they require special faucets that can be operated with very little force or with parts of their bodies other than their hands.
None of these prior art devices fully satisfies the need for a faucet which supplies water just for the time it is needed. In addition, some of these mechanical devices only partially satisfy the needs which they were designed to meet, and they are becoming increasingly more expensive to manufacture.